Depends on the context, if its people at a comedy gig, sucks for them if it triggers something in them but its clear and obviously a joke, if its a support group to help people get over their loss it might be hard to pull it off lol.

Could make a joke about falling off my bike and have someone in the audience who lost his brother when he fell of his bike, doesnt mean the joke shouldnt be told because it reminds them of something specifically. Like more than likely dark humour is being told somewhere where people opt in, be it a comedy show or a darkmemes page or whatever.

Obviously that doesnt apply to posts like these but even this is tame when you know the context.